array: test if key value is not empty before testing if the key is an…

… array.

Signed-off-by: Thibault JUNIN <[email protected]>

src/Validator.php

@@ -271,7 +271,7 @@ public function email(string ...$keys): self
     public function array(string ...$keys): self
     {
         foreach ($keys as $key) {
-            if (!is_array($this->getValue($key))) {
+            if (!empty($this->getValue($key)) && !is_array($this->getValue($key))) {
                 $this->addError($key, ValidationRules::ARRAY);
             }
         }